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Capacitive touch screen interference detection and operation

  • US 9,952,720 B2
  • Filed: 03/29/2012
  • Issued: 04/24/2018
  • Est. Priority Date: 03/29/2011
  • Status: Active Grant
First Claim
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1. A processing system for a capacitive touch screen, said processing system comprising:

  • sensor circuitry configured to be communicatively coupled with sensor electrodes of said capacitive touch screen;

    display circuitry configured to update a display of said capacitive touch screen, wherein the sensor electrodes of the capacitive touch screen comprise a plurality of common electrodes configured to transmit transmitter signals to update the display and to perform capacitive sensing; and

    control logic configured to;

    operate said capacitive touch screen in a first frame type corresponding to a first capacitive sensing sequence that is performed by said plurality of common electrodes within a display sequence, said first frame type comprising a first period for interference detection and a second period for input object capacitive sensing;

    determine, using said first capacitive sensing sequence of said first period of said first frame type, interference in said first frame type, wherein said interference comprises an input object coupled interference component;

    determine, using said first capacitive sensing sequence of said second period of said first frame type, that an input object is in a sensing region of said capacitive touch screen;

    operate, in response to determining that said input object is in the sensing region, said capacitive touch screen in a second frame type without interference detection, wherein said capacitive touch screen operates said plurality of common electrodes at a capacitive sensing frequency that is shifted from said first frame type to said the second frame type, and wherein the control logic is configured to select the second frame type based on said interference that is determined in said first period of said first frame type;

    acquire, using a second capacitive sensing sequence of said second frame type, a capacitive image of the sensing region; and

    filter, using said interference in said first period of said first frame type, the input object coupled interference component from said capacitive image to determine an input object signal in said capacitive image while operating said capacitive touch screen in said second frame type.

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